The choices are not given, however, the question can still be solved.
<u>We know that:</u> pH + pOH = 14 <u>Converting the above equation to concentration form, we will get:</u> [H₃O+] * [OH-] = 10⁻¹⁴
<u>We are given that:</u> concentration of hydroxide ion [OH-] = 1.4 * 10⁻¹⁰ M
<u>Substitute with this in the above equation to get concentration of hydronium ion as follows:</u> [H₃O+] * [OH-] = 10⁻¹⁴ [H₃O+] * [1.4 * 10⁻¹⁰ ] = 10⁻¹⁴ [H₃O+] = [H₃O+] = 7.1428 * 10⁻⁵ M