It’s potentially correct either way. Some people will claim that it has to be singular, as the word “number” is singular. Other people will point out that the notional subject may indeed be plural. In sentence 1, we’re really talking about people (plural), while in sentence 2, we’re talking about a number (i.e. statistics). In 1, people can think, but numbers cannot. In 2, the number has risen, but the products themselves are sitting on shelves, not levitating :)

The subject is "number", which is singular. "Products" is the object of a preposition, not the subject of the sentence.

Hey Albert, Great question. The reason we use HAS in the second sentence is because "number of products" is the subject. Although the word "products" is in plural form, the subject is "number-of-products", so it is treated as singular. (i.e There is only 1 "NUMBER of products", not 2 or more "NUMBERS of products") The difference can be seen where we would say: - The PRODUCTS available in supermarkets HAVE risen sharply In this sentence we use HAVE, as "products" is now the subject and in plural form. I hope this answers your question :)

Hello

Yes, to keep it short, I would say that the subject could be said to be 'The availability' has...