The Nile River supports Egyptian agriculture by A. Supplying extra water for irrigation to supplement annual rains. B. Never flooding. C. Providing easy transport for crops. D. Flooding its banks and depositing rich soil.

The only answer here that has always been false is answer B, although that is now partially true. The river Nile does flood but it no longer floods during the summer because in 1970, the Aswan High Dam was completed. The dam put an end to these massive floods which now occur in a more controlled way, usually in the areas south of the Aswan Dam, and when these floods occur, it does fertilise the soil and ensure it is rich as essential minerals are soaked up into the soil, so answer D is true. It does not flood as dramatically as it once did so not as much soil is left as fertile as it once was. This has fundamentally changed farming habits of all those who grow crops along the river as they may now need to use chemicals or fertilisers to ensure their crops provide good produce.
The dam, commonly referred to as ‘The High Dam’, has dramatically changed life along the river Nile. The floods are now regulated and the dam stores all the water so it can be distributed in a less intense manner for agriculture. The dam also provides hydroelectricity which is a fantastic earner for the Egyptian Government. People can now live in areas which were once inhospitable due to the regular flooding and crops are not destroyed during floods.
Like any river, it provides extra water for those who live in the surrounding areas and supplements annual rainfall and it also provides easy transport for crops so answers A and C are also true. The Nile has long been used to transport goods along its length. Winter winds blow south, up river, so ships could sail either up river, and down river using the flow of the river.

The Nile floods each year, and brings down fresh soil from the south, replenishing the minerals.

Note that for most of the Nile valley, it never rains. There are mud walls in Luxor (ancient Thebes) that are over 2000 years old, they've never been washed away in the rain because there isn't any.
So the Nile is the only source of water for irrigation.
The Nile no longer floods (as a regular thing) - that was stopped by the construction of the Aswan dam. Therefore these days there is no deposit of rich silt - farmers are forced to use chemical fertilisers to keep the soil productive.
The Nile does provide easy transport for crops.