How do i count the number of matching lines using grep?

[hawksbill]

Man page for grep: https://www.lightnetics.com/post/3317

The contents of the file is:

$ cat grepfile
grapes
apples
pears
This is the first block
oranges
plums

grapes
apples
pears
This is the second block
oranges
plums

grapes
apples
pears
This is the third block
oranges
plums

Three lines have the matching string block.

$ grep -c block grepfile
3