The salts nacl and cacl2 (a) are good conductors of electricity (b) have positive charges (c) have the same crystal lattice of energy(d) are held together by ionic bond

Only (d) appears to be correct.

NaCl and CaCl₂ are ionic compounds. Both are made up of charged particles known as ions.

Opposite charges attract each other. So is the case between cations and anions. The two kinds of ions attract each other to produce an ionic lattice. Forces holding them together are known as ionic bonds.

Cations and anions pair up in an ionic compound. Their charges cancel out such that the final compound is neutral. Charged species shall always have a superscript in their formulae that indicates their charge. For example, has positive charges. As a result, it comes with a superscript of "2+". Neither NaCl nor CaCl₂ has a superscript. They are both neutral.

The molar lattice enthalpy of an ionic compound measures the energy released when one mole of it was formed from gaseous ions. This value depends on the size and charge of each ion.

Each mole of CaCl₂ carry four times as much charge as NaCl and three time as much ions. CaCl₂ is expected to have a much higher molar lattice enthalpy.

FYI, the molar lattice enthalpy of NaCl is about -787 kJ/mol (Chemguide). The value for CaCl₂ is -2255 kJ/mol (ACS).