Đoạn mã HTML nào sau đây được sử dụng cho việc upload tập tin trong form?
A. <form enctype="text/plain" action="index.php" method="post">
B. <form enctype="plain" action="index.php" method="post">
C. <form enctype="multipart/form-data" action="index.php" method="post">
D. <form enctype="application/upload-file" action="index.php" method="post">
A. <form enctype="text/plain" action="index.php" method="post">
B. <form enctype="plain" action="index.php" method="post">
C. <form enctype="multipart/form-data" action="index.php" method="post">
D. <form enctype="application/upload-file" action="index.php" method="post">