Answer is choice a, hope that helps
The conventional rule is to take the plural form of the verb when two nouns are joined by the conjunction 'and'. However, there are exceptions. Only then can you break the rule.
When the two nouns refer to one thing only, then you can use the single form. For example: The president and the CEO joins the meeting today. In this example, the president and CEO apply to one person only. Hence, you use the singular form of the verb.
The suffix in this word is -al.
-al as a suffix means "of the kind of, having the characteristics of, being of the kind of ". It's of French or Latin origin
