Having more than the usual numbers of fingers and toes on the hands or feet is termed polydactyly.
A) Having more than the usual numbers of fingers and toes - Incorrect, as the quantifier 'the number' is put in the plural form with the types of fingers or toes;
B) Having had more than the usual numbers of fingers and toes - Incorrect, as the modifier 'having had' is put in the past participle form for the present simple tense;
C) Having more than the usual number of fingers and toes - Correct, as the modifier is responsible for the action and plays the role of subject;
D) To have more than the usual numbers of fingers and toes - Incorrect, 'to verb' is infinitive form of the subject requiring the action to be considered in the cause-effect relationship, whereas this connection implies to be not quite correct here; the connection between the unusual number of fingers and toes and the term named polydactyly is directly specified rather than done in the causal manner;
E) To have more than the usual numbers of fingers and toes - Incorrect, reasons specified in A) and D)