The awards____ the British honours system of titles such as " Sir" and " Lady".

A. were to replace
D. intended to replace

I choose the answer D but the correct answer is B.

Why is the answer B but not D?

Thanks for your help.
Awards are inanimate things and consequently they cannot really intend to do anything. You can't say: A pen intended to write a poem. Only people and animals that have a brain can intend to do something: I intended to cross the street but changed my mind.

Awards, being inanimate, cannot themselves intend to do something. Therefore, "The awards intended to replace..." doesn't make much sense.

"The awards were to replace..." means that it was planned that the awards would replace (the honours system), so is OK.

You could also say "The awards were intended to replace..." which means that someone had an intention about the awards (not that the awards themselves intended anything).